Description

Mod edit, description from MC-46780:
I created a Custom mob spawner using the setblock command, and after it spawned some entities, "Ghost" entities started appearing out of nowhere, these entites cannot be killed by the command /kill @e, and cannot be interacted with in any way

Steps to Reproduce:
1. Create a Superflat world
2. Teleport to (0,0)
3. Use the setblock command to make a Custom spawner, the one I used was:

4. Make the Spawner spawn some entities
5. Notice how out of nowhere "Ghost" entities start to appear

Original description:
When I was creating this custom map in 1.7.4, I wanted to make the map 1.8 ready, so I moved the save file over and I logged in. And I found it. It is a floating Wither Skeleton and floating Blaze on opposite sides of the map. Skeleton is at: 0, 25, -25 and Blaze is at: 0, 25, 25. They are bumping up and down a pixel or so very fast. All the animations on it are right. When I move around in comparison to a block, the Wither Skeleton moves it's location. I can freely build through the Wither Skeleton. It appears to be a graphical glitch or something. Reloading world didn't help, nor did restarting Minecraft. The mobs corresponding spawner is at 0, 50, 50 on both sides. I made the spawners with just the setblock command. This bug does not appear in 1.7.4 when I move the save file in between the versions. It also appears, on the Blaze, when I move around, the particles follow it like it was moving from side to side... They do not despawn in peaceful. I attacked the world, just go through the nether portal at 0,0 in the overworld to get to the area. I do not have any mods installed and I have no idea why this could be happening. I reloaded the world in a different difficulty and it changed from a Wither to a normal Skeleton. Those two are an entity as shown in the F3 screen.

I also did this in the overworld, and the same thing happens, using a pig spawner, a floating pig is now there...

I created a new world in the snapshot and the same thing happens in a normal superflat world too.

Activity

Confirmed; this is really bad, and happens to survival/nocheat spawners (i.e. dungeon spawners) as well.

It appears to be a rendering bug; the phantom entities shift around as the player moves relative to the spawners. Teleporting to 0, 0, 0 aligns each phantom with the corner of its spawner. Moving up will make phantoms move down, and vice versa.

Can you please change the title to "Phantom floating mobs are generated by any spawner (including natural dungeon spawners)", or something similar? It's more descriptive and shows that not only mapmakers get this issue.

WolfieMario
added a comment - 27/Jan/14 2:46 AM Confirmed; this is really bad, and happens to survival/nocheat spawners (i.e. dungeon spawners) as well.
It appears to be a rendering bug; the phantom entities shift around as the player moves relative to the spawners. Teleporting to 0, 0, 0 aligns each phantom with the corner of its spawner. Moving up will make phantoms move down, and vice versa.
Can you please change the title to "Phantom floating mobs are generated by any spawner (including natural dungeon spawners)", or something similar? It's more descriptive and shows that not only mapmakers get this issue.

Attached screenshots from a superflat world. If a spawner is a large distance away, and the player is teleported, they will still see phantoms from the distant spawner - and these phantoms will be stationary, unlike the others. The squid is an example of a distant phantom.

WolfieMario
added a comment - 27/Jan/14 2:55 AM Attached screenshots from a superflat world. If a spawner is a large distance away, and the player is teleported, they will still see phantoms from the distant spawner - and these phantoms will be stationary, unlike the others. The squid is an example of a distant phantom.
Also, similar to how Peaceful won't kill them, /kill won't either, because they aren't real entities (they do, however, still waste client rendering cycles).

I suppose it could, although the mob inside appears as normal. I'm guessing it's related to that, however.

There used to be a bug where spawners with stacked entities would only show the topmost entity spinning in the cage, and the rest would appear elsewhere in the world full-size. Unlike the phantoms you found, these would be effected by gravity and prevent players from placing blocks or attacking real entities, but other than that, it's very similar.

WolfieMario
added a comment - 27/Jan/14 3:04 AM I suppose it could, although the mob inside appears as normal. I'm guessing it's related to that, however.
There used to be a bug where spawners with stacked entities would only show the topmost entity spinning in the cage, and the rest would appear elsewhere in the world full-size. Unlike the phantoms you found, these would be effected by gravity and prevent players from placing blocks or attacking real entities, but other than that, it's very similar.

Is there a way to say to mojang that, "This is a bug that needs to be fixed?"

They should add a drop down with how crucial the bug is. Like if it is something that crashes the world, you would say, "Threat to world" if it is something like the cactus being rendered incorrectly or the relmes cancel button misplaced, those should be "Graphical Glitch" or something. Something to rate the bug. So if you find something that is very bad for your world, and nobody else has seen it, or it is very rare, you could say, "Threat to world" and it would be put higher in mojang's priority list.

Christopher Smith
added a comment - 04/Feb/14 3:43 PM Is there a way to say to mojang that, "This is a bug that needs to be fixed?"
They should add a drop down with how crucial the bug is. Like if it is something that crashes the world, you would say, "Threat to world" if it is something like the cactus being rendered incorrectly or the relmes cancel button misplaced, those should be "Graphical Glitch" or something. Something to rate the bug. So if you find something that is very bad for your world, and nobody else has seen it, or it is very rare, you could say, "Threat to world" and it would be put higher in mojang's priority list.